Enhancing the mechanical properties of high strain rate rolled Mg–6Zn–1Mn alloy by pre-rolling

The effect of pre-rolling prior to the high strain rate rolling (HSRR) on the dynamic recrystallization (DRX), dynamic precipitation and mechanical properties of Mg–6Zn–1Mn (ZM61) was investigated. Aiming this, a set of pre-rolling tests were carried out at the temperature of 300 °C with pre-rolling strain of 20 and 40%. The results show that pre-rolling treatment greatly homogenize the microstructure and refine DRX grains. The original twins induced by pre-rolling accelerate the DRX process and provide more nucleation sites for DRX grains. The precipitates induced by pre-rolling increase the precipitation density and lead to a strong interaction between DRX grains and precipitates. The ZM61 alloy sheet prepared with 20% pre-rolling strain at 300 °C followed by HSRR at 300 °C exhibits the UTS of 392 MPa and elongation of 16.8%. The advanced mechanical properties can be ascribed to the combined effect of grain refinement hardening and nano-precipitation strengthening.